U.S. patent application number 13/027065 was filed with the patent office on 2011-12-22 for vacuum valve apparatus and method.
Invention is credited to Ronald Flanary, William W. Griffith, Howard Keith Kidd, Kenneth Sowers, Jeffrey S. Terrell.
Application Number | 20110308629 13/027065 |
Document ID | / |
Family ID | 44368195 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110308629 |
Kind Code |
A1 |
Griffith; William W. ; et
al. |
December 22, 2011 |
Vacuum Valve Apparatus and Method
Abstract
Embodiments of the invention provide a vacuum valve apparatus
and method to provide a vacuum to equipment. The vacuum valve can
include an air port tube, a vacuum port tube, a motor, and a
control arm coupled to the vacuum port tube and the motor. The
motor can cause the control arm to move in an arc in order to flex
the vacuum port tube and selectively create the vacuum and vent the
vacuum provided to the equipment.
Inventors: |
Griffith; William W.;
(Dublin, VA) ; Flanary; Ronald; (Blacksburg,
VA) ; Terrell; Jeffrey S.; (Port Matilda, PA)
; Kidd; Howard Keith; (Christiansburg, VA) ;
Sowers; Kenneth; (Riner, VA) |
Family ID: |
44368195 |
Appl. No.: |
13/027065 |
Filed: |
February 14, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61304138 |
Feb 12, 2010 |
|
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|
Current U.S.
Class: |
137/14 ;
137/487.5 |
Current CPC
Class: |
F16K 7/02 20130101; Y10T
137/7761 20150401; Y10T 137/87788 20150401; F16K 51/02 20130101;
Y10T 137/0396 20150401 |
Class at
Publication: |
137/14 ;
137/487.5 |
International
Class: |
F15D 1/00 20060101
F15D001/00 |
Claims
1. A vacuum valve that provides a vacuum to equipment, the vacuum
valve comprising: an air port tube; a vacuum port tube; a motor;
and a control arm coupled to the vacuum port tube and the motor,
the motor causing the control arm to move in an arc in order to
flex the vacuum port tube and selectively create the vacuum and
vent the vacuum provided to the equipment.
2. The vacuum valve of claim 1, wherein the motor is a servo
motor.
3. The vacuum valve of claim 2, wherein the servo motor is
controlled in order to tailor a rate of change of the vacuum
without substantially slowing down an overall cycle time.
4. The vacuum valve of claim 3, wherein the servo motor is
controlled in order to decelerate the control arm as the control
arm approaches a valve base.
5. The vacuum valve of claim 4, and further comprising a stop
member to prevent the control arm from rotating past the valve base
when it approaches the valve base.
6. The vacuum valve of claim 1, wherein when the control arm
includes a first end coupled to a shaft of the motor and a second
end including an aperture through which the vacuum port tube is
positioned.
7. The vacuum valve of claim 1, and further including a support
panel, an air port bracket, and a vacuum port bracket, wherein the
air port bracket supports the air port tube, the vacuum port
bracket supports the vacuum port tube, and the support panel
supports at least one of the air port bracket, the vacuum port
bracket, and the motor.
8. The vacuum valve of claim 1, wherein the motor causes the
control arm to move to a vacuum position in order to create the
vacuum provided to the equipment by aligning the vacuum port tube
with the air port tube.
9. The vacuum valve of claim 8, wherein the vacuum port tube is
positioned relative to the air port tube so that there is a
clearance between the vacuum port tube and the air port tube when
in the vacuum position.
10. The vacuum valve of claim 9, and further comprising a clearance
adjustment mechanism for adjusting the amount of clearance between
the vacuum port tube and the air port tube when in the vacuum
position.
11. The vacuum valve of claim 1, wherein the motor causes the
control arm to move to a vent position in order to vent the vacuum
provided to the equipment by flexing the vacuum port tube away from
the air port tube and allowing ambient air into the air port
tube.
12. The vacuum valve of claim 1, wherein the arc is about an
approximately ten-degree arc.
13. The vacuum valve of claim 12, wherein the motor causes the
control arm to move the full ten-degree arc within about 10
milliseconds to about 12 milliseconds.
14. The vacuum valve of claim 1, wherein the vacuum port tube
provides a 100% swept flow path of the vacuum to the equipment.
15. The vacuum valve of claim 1, wherein the motor and the control
arm are positioned external from a vacuum stream through the vacuum
port tube.
16. A method for selectively providing a vacuum to equipment, the
method including: providing a vacuum valve including an air port
tube, a vacuum port tube, a motor, and a control arm coupled to the
vacuum port tube and the motor; creating the vacuum provided to the
equipment by rotating the control arm to a vacuum position so that
the air port tube and the vacuum port tube are aligned relative to
each other; and venting the vacuum provided to the equipment by
rotating the control arm to a vent position so that the vacuum port
tube is flexed in an arc away from the air port tube.
17. The method of claim 16, and further comprising operating the
motor to rotate the control arm in the arc from the vacuum position
to the vent position in about ten milliseconds to about twelve
milliseconds.
18. The method of claim 17, and further comprising decelerating the
motor in the last about three to four degrees of the arc as the
control arm rotates from the vent position to the vacuum
position.
19. The method of claim 17, wherein the motor rotates the control
arm in an approximately ten-degree arc.
20. The method of claim 16, and further comprising providing a
clearance between the vacuum port tube and the air port tube in the
vacuum position.
Description
RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.119
to U.S. Provisional Patent Application No. 61/304,138 filed on Feb.
12, 2010, the entire contents of which is incorporated herein by
reference.
BACKGROUND
[0002] In high speed automation, vacuum valves are capable of
building a vacuum and shutting off a vacuum quickly. Many processes
are gated by the speed at which this can occur. One example of such
an application is vacuum gripper devices used to pick up and move
mail, envelopes, and/or paper. Conventional vacuum valves must be
replaced frequently due to short life spans.
[0003] One type of conventional vacuum valve is a packed spool
valve. The spool is generally a cylindrical piece located in the
center of the valve that is actuated back and forth by compressed
air. Sealing surfaces on the spool, e.g., vulcanized rubber, slide
back and forth across a highly polished sleeve, changing the
connection paths from input to output as the spool moves.
[0004] A conventional packed spool valve is typically designed for
air filtered to 40 microns. However, 5 micron filtration is
desirable for demanding applications and long valve life. Due to
the nature of the application and the very high speed switching of
vacuum to vent and corresponding vacuum decay times needed, the
incorporation of a filter in order to achieve this level of
filtration is neither possible nor practical. Also, the
incorporation of a filter to protect the inner workings of the
packed spool valve would necessitate a large preventative
maintenance operation to change up to 10 separate filters on each
machine in a very short replacement cycle. As a result, the
internal working components of the packed spool valve are subject
to a high degree of particulates of varying size and type, the
majority being paper dust, which is very abrasive and also which
builds-up inside the valve causing it to leak or otherwise fail due
to contamination. The sealing of the packed spool valve is
dependent upon the close mating of the vulcanized spool with the
inner surface of the sleeve. Conventional packed spool valves last
about three to four months in operation before the level of
contamination causes them to fail.
SUMMARY
[0005] Embodiments of the invention provide a vacuum valve that
provides a vacuum to equipment. The vacuum valve can include an air
port tube, a vacuum port tube, a motor, and a control arm coupled
to the vacuum port tube and the motor. The motor can cause the
control arm to move in an arc in order to flex the vacuum port tube
and selectively create the vacuum and vent the vacuum provided to
the equipment. The motor can be a servo motor than can be
controlled in order to tailor a rate of change of the vacuum
without substantially slowing down an overall cycle time.
[0006] Some embodiments of the invention provide a method for
selectively providing a vacuum to equipment. The method can include
creating the vacuum provided to the equipment by rotating the
control arm to a vacuum position so that the air port tube and the
vacuum port tube are aligned relative to each other. The method can
further include venting the vacuum provided to the equipment by
rotating the control arm to a vent position so that the vacuum port
tube is flexed in an arc away from the air port tube.
DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a top perspective view of a vacuum valve according
to one embodiment of the invention.
[0008] FIG. 2 is a bottom perspective view of the vacuum valve of
FIG. 1.
[0009] FIG. 3 is an exploded bottom perspective view of the vacuum
valve of FIG. 1.
[0010] FIG. 4 is an exploded top perspective view of the vacuum
valve of FIG. 1.
[0011] FIG. 5 is a side view of the vacuum valve of FIG. 1.
[0012] FIG. 6 is bottom view of the vacuum valve of FIG. 1.
[0013] FIGS. 7A-7E are perspective views of vacuum valves according
to alternative embodiments of the invention.
DETAILED DESCRIPTION
[0014] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless specified or limited otherwise,
the terms "mounted," "connected," "supported," and "coupled" and
variations thereof are used broadly and encompass both direct and
indirect mountings, connections, supports, and couplings. Further,
"connected" and "coupled" are not restricted to physical or
mechanical connections or couplings.
[0015] The following discussion is presented to enable a person
skilled in the art to make and use embodiments of the invention.
Various modifications to the illustrated embodiments will be
readily apparent to those skilled in the art, and the generic
principles herein can be applied to other embodiments and
applications without departing from embodiments of the invention.
Thus, embodiments of the invention are not intended to be limited
to embodiments shown, but are to be accorded the widest scope
consistent with the principles and features disclosed herein. The
following detailed description is to be read with reference to the
figures, in which like elements in different figures have like
reference numerals. The figures, which are not necessarily to
scale, depict selected embodiments and are not intended to limit
the scope of embodiments of the invention. Skilled artisans will
recognize the examples provided herein have many useful
alternatives and fall within the scope of embodiments of the
invention.
[0016] FIGS. 1-6 illustrate a vacuum valve or "flipper" valve 10
according to one embodiment of the invention. As shown in FIG. 1,
the vacuum valve 10 can include a motor 12, an air port 14, a
vacuum port 16, a support panel 18, an air port bracket 20, a
vacuum port bracket 22, an air port tube 24, and a vacuum port tube
26. The motor 12 is coupled to the support panel 18, which can be a
substantially horizontal plate including several apertures, in some
embodiments. The motor 12 can be a permanent magnet brushless servo
motor or a stepper motor. The air port bracket 20 and the vacuum
port bracket 22 can each be coupled to a bottom portion of the
support panel 18 by suitable fasteners, such as bolts 23. In one
embodiment, the support panel 18, the air port bracket 20, and/or
the vacuum port bracket 22 can be machined from an aluminum block.
The working surfaces can be precision machined in order to help
achieve low-leakage of air and to help prevent the rubbing of
parts.
[0017] The air port tube 24 can be positioned through an aperture
25 in the air port bracket 20. The air port bracket 20 can include
a bottom mounting portion 28 including one or more mounting
recesses 30 that can be used to fasten the vacuum valve 10 to other
equipment. The vacuum port tube 26 can be positioned through an
aperture 27 in the vacuum port bracket 22.
[0018] As shown in FIG. 2, the motor 12 can be coupled to the
support panel 18 so that a motor shaft 32 is positioned through an
aperture 34 in the support panel 18. The vacuum valve 10 includes a
control arm 36 with a first end 38 coupled to the motor shaft 32
and a second end 40 coupled to the vacuum port tube 26. The first
end 38 can include a right-angle portion 42 including an aperture
44 through which the motor shaft 32 can be positioned. The first
end 38 can be integrally coupled to a beam 46, which can be
integrally coupled to the second end 40. The second end 40 can
include an aperture 48 through which the vacuum port tube 26 is
positioned. Although shown as being broken in FIGS. 1-4 and 6 in
order to illustrate the control arm 36, the vacuum port tube 26 is
a continuous, unbroken tube between the second end 40 of the
control arm 36 and the vacuum port bracket 22, as shown in FIG.
5.
[0019] When the control arm 36 is in an open position, as shown in
FIG. 2, a vacuum can be created by drawing ambient air from the air
port tube 24 to the vacuum port tube 26. The air port tube 24 is
coupled to automated pneumatic equipment, such as a vacuum gripper
device used to pick up and move mail, envelopes, sheets of paper,
etc. The vacuum occurs at the end of the air port tube 24 where it
is coupled to the automated pneumatic equipment (i.e., the vacuum
is transferred to the "work" at the end of the air port tube
24).
[0020] In order to break or vent the vacuum, the control arm 36 can
rotate about the motor shaft 32 in order to move in an arc A (as
shown in FIGS. 2 and 6) into a closed position (not shown). As the
control arm 36 moves in the arc A away from the air port bracket
20, the vacuum port tube 26 flexes. The second end 40 of the
control arm 36, and with it the vacuum port tube 26, breaks away
from the air port tube 24 at a valve base 50. This allows ambient
air into the air port tube 24, breaking the vacuum to the work, and
can also place the vacuum port tube 26 over a solid surface,
blocking the vacuum at the vacuum port tube 26 for the next
cycle.
[0021] The control arm 36 of the vacuum valve 10 can move back and
forth in the arc A in order to function as a high-speed three-way
vacuum control valve. The vacuum valve 10 can be a normally-closed
valve that switches its output between vacuum and vent. The
positions of the vacuum valve 10 can be initiated on-demand by a
machine controller connected to the motor 12. As shown in FIG. 2,
the motor 12 can include a power connector 54 and a communication
connector 56. The motor 12 can be in electrical communication with
a machine controller through the communication connector 56 (e.g.,
using CAN bus communication or Device Net communication). The motor
12 can include an internal controller that can be in communication
with the machine controller. The controller can be positioned
within the housing of the motor 12 in order to keep dust and
contaminants away from the electronics.
[0022] In one embodiment, the overall cycle time of the control arm
36 can average about 167 milliseconds (ms) from a closed position
to the next closed position. In one embodiment, movement of the
control arm 36 from the open position to the closed position and
from the closed position to open position can occur in about ten ms
to about twelve ms and can represent about a ten-degree movement of
the control arm 36 by the motor 12. In some embodiments, the vacuum
valve 10 can include a stop member 52 to help prevent the control
arm 36 from rotating beyond the valve base 50.
[0023] The control arm 36 is positioned in the vacuum (open)
position or the vent (closed) position to alternately supply vacuum
or ambient air to the work. In the vent position, the vacuum supply
can be blocked. The control arm 36 can move laterally to a closed
position to prevent loss of source vacuum. This movement also opens
the air port 14 to atmosphere, venting the work.
[0024] Referring to FIGS. 2 and 5, the valve base 50 appears to be
in close physical contact with a front face of the second end 40 of
the control arm 36. In some embodiments, a clearance can exist
between the valve base 50 of the air port bracket 20 and the second
end 40 of the control arm 36. In some embodiments, the clearance
can be adjusted in order to alter the performance of the vacuum
valve 10. For example, the clearance can be adjusted in order to
prevent undue leakage of vacuum. However, in some embodiments, a
small amount of clearance can be desirable for the following
reasons: (1) a low leak rate still preserves vacuum level; (2)
operating with some clearance eliminates moving parts that are in
contact, extending the life of the vacuum valve 10; and (3) a small
amount of leakage can create air-flow over the moving parts, which
cleans the working surfaces during operation. In some embodiments,
the valve base 50 of the air port bracket 20 can be machined very
accurately (e.g., about 0.002 of an inch to about 0.004 of an inch
of working clearance). A clearance adjustment mechanism can be
incorporated into the vacuum valve 10, for example, using the
fasteners 23 through the support panel 18.
[0025] In some embodiments, the vacuum valve 10 can include one or
more of the following characteristics or performance
specifications: (1) an effective area of about 244 mm.sup.2; (2) a
vacuum level of about 500 mbar (-50 kPa) working, 600 mbar (-60
kPa) design; (3) ability to impart a force of about 12.3 Newtons
(2.76 pounds) at 500 mbar to the control arm 36 due to vacuum
pressure acting on the working area; and (4) ability to overcome
rotational inertia of the control arm 36 of about 37 kg
mm.sup.2.
[0026] An additional load on the motor 12 can be due to the weight
and stiffness of the flexible vacuum port tube 26. As a result, the
vacuum port tube 26 may be light weight to reduce inertia and very
flexible to provide for long life and to minimize the moment forces
on the control arm 36. In one embodiment, the vacuum port tube 26
is rated for a maximum inlet vacuum of about 600 mbar.
[0027] In some embodiments, the on/off response time of the vacuum
valve 10 can be about 10 ms to about 12 ms. In some embodiments, it
can take about 2 ms after the control arm 36 moves back to the
valve base 50 to build up to 95% of full vacuum (i.e., development
time). In some embodiments, the vacuum valve 10 has a
move-plus-vacuum development time of about 14 ms. In addition, it
can take about 2 ms after the control arm 36 moves away from the
valve base 50 for the vacuum to adequately decay. In some
embodiments, the vacuum off time can be about 14 ms including 2 ms
of decay time. The vacuum can be said to be "on" when the vacuum
pressure is at 95% of design vacuum (e.g., 500 mbar.times.0.95=475
mbar).
[0028] In some embodiments, the vacuum valve 10 can have an
operating frequency of about 6 Hz on-demand from a machine
controller. The operation of the vacuum valve 10 can be initiated
by a 24 Volt, direct current (V.sub.DC) discrete signal from the
machine controller. The machine controller can provide two signals:
one for open and one for closed. In some embodiments, the vacuum
valve 10 can have a design operating frequency of about 33 Hz. In
some embodiments, the vacuum valve 10 can have a design life of
about 10 operational years or about 1.9 billion cycles.
[0029] In some embodiments, it may be desirable to have only one
input signal from the machine controller in order to preserve
input/output on the machine (e.g., a vacuum gripper). Holding the
signal "on" can place the vacuum valve input/output in the open
(vacuum) position. When the signal is turned off, the vacuum valve
10 can close (vent). The vacuum valve 10 can spend the majority of
time in the closed (vent) position. In one embodiment, the vacuum
valve 10 can provide an "enable" signal to the machine controller
of 24 V.sub.DC PNP.
[0030] Lubrication of the vacuum valve 10 working surfaces may
generally not be required or be only minimally required. The air
port tube 24 and the vacuum port tube 26 can be 3/4-inch hoses for
a tube-to-tube version of the vacuum valve 10. The vacuum valve 10
can include a 3/4-inch vacuum hose supply connection and integrated
belt vacuum plenum output for a vacuum-belt version of the vacuum
valve 10.
[0031] The working components of the vacuum valve 10 (e.g., the
moving parts of the control arm, the motor, etc.) are external to
the flow, and thus, are not subject to the effects of the
contaminants found in the vacuum stream. Since the vacuum is
controlled right in the vacuum plenum behind the belt, the vacuum
decay times can be much shorter than that of conventional valves
that need to be remotely mounted due to their size and
configuration. Another benefit of the vacuum valve 10 is that it
features a 100% swept flow path. The swept flow prevents build-up
of contaminants in the vacuum stream because there are no dead
zones that would encourage any build-up.
[0032] In some embodiments, the acceleration and deceleration of
the control arm 36 can be controlled so that the control arm 36
does not vibrate upon stopping, nor impact the limits of the valve
base 50 and create noise and/or deterioration of the working
surfaces due to the impact. In these embodiments, the motor 12 can
be a permanent magnet brushless servo motor. The servo motor 12 can
include an integrated position loop to position the vacuum port
tube between two points (e.g., a point A where the vacuum engages
and a point B where the vacuum is disengaged). The motion between
the vacuum being engaged and the vacuum being disengaged can be
accomplished very fast (e.g., less than about 0.012 seconds).
[0033] In some applications using conventional vacuum valves, the
rate of change from no vacuum to full vacuum is too fast and
results is tearing or damaging the part onto which the vacuum was
applied. The vacuum valve 10 can have the ability to adjust the
speed profile so that the rate of change associated with the vacuum
turn-on can be tailored for the specific application. For example,
if the control arm 36 moves about ten degrees, the control arm 36
can be slowed down (decelerate) during the last three to four
degrees of movement. This can provide an advantage in applications
where fragile components (such a letters) are handled. As a result,
in some embodiments, the vacuum valve 10 can tailor the rate of
change of the vacuum (i.e., of the vacuum turn-on and/or vacuum
turn-off) without substantially slowing down the overall cycle of
alternate vacuum and venting.
[0034] FIGS. 7A-7E illustrate various alternative designs of vacuum
valves according to embodiments of the invention.
[0035] It will be appreciated by those skilled in the art that
while the invention has been described above in connection with
particular embodiments and examples, the invention is not
necessarily so limited, and that numerous other embodiments,
examples, uses, modifications and departures from the embodiments,
examples and uses are intended to be encompassed by the claims
attached hereto. The entire disclosure of each patent and
publication cited herein is incorporated by reference, as if each
such patent or publication were individually incorporated by
reference herein. Various features and advantages of the invention
are set forth in the following claims.
* * * * *